This invention relates to a light weight, tapered tubular structure that provides superior performance for a wide variety of applications, especially in golf club shafts, but also in other products such as fishing rods, ski poles and other such applications. The invention also provides a method for making the unique structural member.
The outstanding characteristics and benfits that the structure of this invention offers over products of the prior art are especially described in this specification with reference to golf club shafts as an example. However, as will be readily apparent to those skilled in the art, the product and method for producing the product of this invention provide superior characteristics for many applications where a material is desired that provides low weight in combination with high strength, high resistance to torsional forces, various desired degrees of longitudinal flexure, high tip breaking strength, a center of gravity more favorably located toward the tip-end than in state-of-the-art products, along with excellent stability, good impact strength, long endurance life, and high fatigue strength.
Spirally wound or helically wound products per se are old in the art and have been used many years in producing products of fabrics and of fibers such as fiberglass, and more recently from more advanced fibers such as graphite. However, such spirally wound products typically are produced by simply winding the fibers at a uniform wrapping angle or wrapping speed in any given layer of the resulting structure. Such typical helically wound fiber shafts are described, for instance, in U.S. Pat. No. 2,573,361 and U.S. Pat. No. 3,457,692. There are also numerous references to fibers placed in layers on shafts or other tubular products, such as described in the above-mentioned patents. Other innovations in golf club shafts that show methods of construction used in the prior art can be found in U.S. Pat. Nos. 3,166,319; 2,822,175; 2,934,345; 3,313,541; 3,646,610, and related composite structures can be produced as described in U.S. Pat. No. 3,691,000.
None of these patents or any other known prior art specifically uses or claims the unique features of the new product of this invention, which achieves the following benefits over all products of the known prior art.